This invention relates to corona wire cartridges of the type used on photocopiers, laser printers and the like, and more particularly, to a method and apparatus for replacing a worn or broken corona wire on such cartridges while utilizing the original equipment cartridge framework.
Existing corona wire cartridges are disclosed at U.S. Pat. Nos. 4,626,701; 3,499,143; 4,754,305; and 4,864,363. The "701" patent discloses a corona wire cartridge sold under the trademark Canon wherein the corona wire is suspended across an elongate opening in the cartridge and permanently mounted on the opposing ends of the cartridge by rivets. Tension is placed on the corona wire by means of a pair of rollers also mounted on each end of the cartridge which press on the corona wire when installed. The "363" patent discloses a corona wire cartridge sold under the trademark Ricoh, wherein the cartridge includes a post-type mounting and the corona wire includes a metal eyelet at one end which is mounted on one post, and a coil tension spring mounted on the opposing post. A loop end of the coil spring is a retainer for an opposing looped end of the corona wire.
At the present time, maintenance persons in the field, by and large, replace entire corona wire cartridges when the wire ceases to function properly, that is, when it is corroded or breaks. As an alternative to replacing an entire corona wire cartridge, maintenance repair people have been supplied with coils of tungsten wire which, if they desire and have the sufficient technical knowledge and ability, may be cut to proper lengths and hand fitted to old cartridges. To date, hand made corona wire replacements made from long coils of tungsten wires have, in the main, proven not as satisfactory as replacing the entire corona wire cartridge.
A need has developed for pre-made individual replacement corona wires, and apparatus for mounting those corona wires to existing corona wire cartridges so as to save the expense of purchasing an entire replacement corona wire cartridge while at the same time providing a replacement unit which provides the quality of operation of an original corona wire cartridge assembly.
It is therefore an object of the present invention, generally stated, to provide an improved means for rewiring a corona wire cartridge by providing apparatus for modifying present cartridge to accept the new pre-made corona wire assembly, and by providing an improved method of retrofitting corona wire cartridges with the new replacement wire assembly.